From understanding to realizing novel III-Sb materials via nanowires
Author
Summary, in English
Due to their unique physical and material properties, III-Sb nanowires are considered good candidates for future devices, and test beds for understanding fundamental physics. Synthesizing these nanowires however is associated with certain challenging aspects, which are generally not present for other III-V nanowires, demanding the need for in depth investigations. For instance, growing Au-seeded III-Sb nanowires directly from substrates is difficult, and considered a limitation when attempting to grow complex Sb-based structures. The crystal structure of III-Sb nanowires, in contrast to their other III-V counterparts, has been limited to zinc blende to date, with no reproducible reports on wurtzite antimonides. As the crystal structure of material has a large impact on the properties it exhibits, it can be beneficial to have access to wurtzite antimonides. To further the capacity antimonide nanowires can offer, these struggles need to be investigated and addressed through suitable methods. This thesis explores these limitations, and by providing a deeper insight, tackles the mentioned issues of Au-seeded III-Sb nanowire growth.
Initially direct nucleation of Au-seeded InAs1-xSbx nanowires with a large range of material compositions is explored. Direct growth of nanowires with compositions on the higher end of Sb is made available through semi In-seeded growth. By changing the particle composition the contact angle is improved, and vertical nanowire growth is facilitated.
Thereafter, through template assisted growth, complex multi-segmented selective core-shell structures of InAs-GaSb nanowires are realized. The antimonide shell will exclusively grow on the zinc blende segments of the underlying InAs core, as a result of the higher surface energy of zinc blende sidewalls.
Finally, the thesis successfully examines various templating methods for realizing radial (GaSb), branched (InAs1-xSbx), and axial (1D) (GaSb) wurtzite antimonides for the first time. The mechanisms leading to surmounting wurtzite antimonide formation barriers are explained in detail for each of the specific cases, leading to a thorough
comprehension of the field. These methods, in combination with the possibility to now realize antimonide nanowires directly on substrates, opens doors towards design and synthesis of complex crystal structure engineered nanowires
of pure antimonides.
Initially direct nucleation of Au-seeded InAs1-xSbx nanowires with a large range of material compositions is explored. Direct growth of nanowires with compositions on the higher end of Sb is made available through semi In-seeded growth. By changing the particle composition the contact angle is improved, and vertical nanowire growth is facilitated.
Thereafter, through template assisted growth, complex multi-segmented selective core-shell structures of InAs-GaSb nanowires are realized. The antimonide shell will exclusively grow on the zinc blende segments of the underlying InAs core, as a result of the higher surface energy of zinc blende sidewalls.
Finally, the thesis successfully examines various templating methods for realizing radial (GaSb), branched (InAs1-xSbx), and axial (1D) (GaSb) wurtzite antimonides for the first time. The mechanisms leading to surmounting wurtzite antimonide formation barriers are explained in detail for each of the specific cases, leading to a thorough
comprehension of the field. These methods, in combination with the possibility to now realize antimonide nanowires directly on substrates, opens doors towards design and synthesis of complex crystal structure engineered nanowires
of pure antimonides.
Publishing year
2018-02-27
Language
English
Full text
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Document type
Dissertation
Publisher
Solid State Physics, Lund University
Topic
- Engineering and Technology
Keywords
- Fysicumarkivet A:2018:Namazi
Status
Published
ISBN/ISSN/Other
- ISBN: 978-91-7753-586-7
- ISBN: 978-91-7753-585-0
Defence date
23 March 2018
Defence time
09:15
Defence place
Lecture hall Rydbergsalen, Fysicum, Professorsgatan 1, Lund University, Faculty of Engineering LTH.
Opponent
- Hannah Joyce (Dr)